Resin-based dental restorative materials are extensively used today in dentistry. However, significant concerns still remain regarding their biocompatibility. For this reason, significant scientific effort has been focused on the determination of the molecular toxicology of substances released by these biomaterials, using several tools for risk assessment, including exposure assessment, hazard identification and dose-response analysis. These studies have shown that substances released by these materials can cause significant cytotoxic and genotoxic effects, leading to irreversible disturbance of basic cellular functions. The aim of this article is to review current knowledge related to dental composites’ molecular toxicology and to give implications for possible improvements concerning their biocompatibility.

©Operative Dentistry, 2007, 32-4, 406-411 A Sarafianou • S Iosifidou T Papadopoulos • G Eliades Clinical RelevanceAccelerated hydrothermal-and photo-aging of direct light-cured composite restorative materials induced visually perceptible but clinically acceptable total color changes, along with a reduction in the amount of remaining C=C bonds. SUMMARYPurpose: This study evaluated the color changes and amount of remaining C=C bonds (%RDB) in three dental composites after hydrothermal-and photoaging. Methods and Materials: The materials tested were Estelite Σ, Filtek Supreme and Tetric Ceram. Specimens were fabricated from each material and subjected to L* a* b* colorimetry and FTIR spectroscopy before and after aging. Statistical evaluation of the ΔL,* Δa,* Δb,* ΔE and %ΔRDB data was performed by one-way ANOVA and Tukey's test. The %RDB data before and after aging were statistically analyzed using two-way ANOVA and Student-Newman-Keuls test. In all cases an α=0.05 significance level was used. Results: No statistically significant differences were found in ΔL*, Δa*, ΔE and %ΔRDB among the materials tested. Tetric Ceram demonstrated a significant difference in Δb*. All the materials showed visually perceptible (ΔE>1) but clinically acceptable values (ΔE<3.3). Within each material group, statistically significant differences in %RDB were noticed before and after aging (p<0.05). Filtek Supreme presented the lowest %RDB before aging, with Tetric Ceram presenting the lowest %RDB after aging (p<0.05). The %ΔRDB mean values were statistically significantly different among all the groups tested. No correlation was found between ΔE and %ΔRDB.

Valplast was found to have a significantly lower gloss and a higher roughness than Paladon 65 before cleansing. After cleansing, ΔE* increased more in Valplast than in Paladon 65, gloss of both materials decreased and roughness only of Paladon 65 increased within the Corega extradent plus microwaving method.

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A seismological network of 10 portable analogue stations was installed in the area of Heraklion (central Crete) from September to December 1995. During this period, more than 1000 events were recorded by at least 4 stations with magnitudes ranging from 0.5 to 4.6 and depths up to 70 km. Analysis of 336 well located events revealed high seismic activity. In the onshore area seismicity is shallow (<20 km) and concentrated along the eastern margin of the Heraklion Basin and in the Messara graben to the south. Seismicity decreases rapidly from east to west, with practically no events located along the western boundary of Heraklion Basin. Epicenter distribution indicates that microseismicity is closely associated to the tectonics of the region. Significant seismic activity was also observed in the southern offshore area, restricted north of the Hellenic Trench and related to the subduction process. The determination of different types of focal mechanisms in the area indicates that the investigated region is characterized by complex tectonics related to the southward subduction of the African plate and the northward extension of the Aegean lithosphere.